The present invention relates to an image forming apparatus.
The service life of the image bearing member, or the like, of an image forming apparatus is shorter than that of the main assembly of the image forming apparatus. Therefore, it is a common practice to render the image forming member or the like exchangeably mountable in the main assembly by placing it in a cartridge, or a so-called process cartridge.
A process cartridge needs to receive driving force from the main assembly of an image forming apparatus in which it is mounted.
In one of the methods for transmitting driving force from the main assembly of an image forming apparatus to a process cartridge, the drive shaft on the process cartridge side is directly connected to the drive shaft on the apparatus main assembly side, eliminating the need for driving force transmission gears. In other words, driving force is transmitted through a simple structure.
However, if a process cartridge is provided with a plurality of members to be driven by the driving force transmitted thereto from the apparatus main assembly side, it is rather difficult to accurately position the drive shafts of the plurality of members on the process cartridge side so that they perfectly align with the corresponding drive shafts on the apparatus main assembly side.
In a structural arrangement in which a drive shaft is connected to a drive shaft in a virtually straight line as described above, if the position of a drive shaft on the driving side, or a driving shaft, and the position of a drive shaft on the driven side, or a driven shaft, are misaligned in terms of the axial direction of the drive shaft and driven shaft before they are connected, the two shafts become connected in such a manner that their rotational axes remain slanted relative to each other. Such connection makes the contact points between the two shafts nonuniform in terms of the amount of the driving force transmitted through each contact point. As a result, a certain amount of driving force is diverted from the direction in which the driving force is to be transmitted, causing a process cartridge to vibrate.
The primary object of the present invention is to provide an image forming apparatus, in which even if the shafts of the plurality of components within a process cartridge having been removably mounted in the main assembly of the image forming apparatus are not in perfect alignment with the corresponding drive shafts on the apparatus main assembly side, a driving force is transmitted from the driving shafts, or the drive shafts on the main assembly side, to the shafts to be driven, or the shafts on the process cartridge side, without causing vibrations.
According to an aspect of the present invention, there is provided an image forming apparatus comprising: a process unit detachably mountable to a main assembly of said apparatus, said process unit including an image bearing member for bearing an electrostatic image and process means actable on said image bearing member, said process means having a rotational shaft; a driving shaft, substantially co-axial with said rotational shaft, for rotating said rotational shaft; and a drive transmitting member, engaged with said driving shaft and with said rotational shaft, for transmitting a driving force to said rotational shaft from said driving shaft, wherein said drive transmitting member is engaged with said driving shaft with a play and is engaged with said rotational shaft with a play.
According to another aspect of the present invention, there is provided a process cartridge detachably mountable to an image forming apparatus, said process cartridge comprising an image bearing member for bearing an electrostatic image; process means actable on said image bearing member, said process means including a rotational shaft; and a drive transmitting member for receiving a driving force from a driving shaft provided in a main assembly of the apparatus; wherein said drive transmitting member is engageable with said driving shaft with a play and is engaged with said rotational shaft with a play.
According to a further aspect of the present invention, it is preferable that in said apparatus, said image bearing member has a rotational shaft which is engaged with a driving shaft provided in the main assembly of the apparatus with a play which is smaller than the play with which said drive transmitting member is engaged with said driving shaft or with said rotational shaft.
According to a further aspect of the present invention, it is preferable that in said process cartridge, said image bearing member has a rotational shaft which is engageable with a driving shaft provided in the main assembly of the apparatus with a play which is smaller than the play with which said drive transmitting member is engaged with said driving shaft or with said rotational shaft.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.